How we learn about The Quoin from aerial images
Looking at Stocker's Bottom from 1949 to now.
The landscapes we love were here long before us, and will continue long afterwards: we are custodians for a period, and if we do it right, we leave the land better than we found it. So we need to think in time as well as space, to understand what came before, so that we can imagine what it might become.
The northern part of The Quoin contains a large open valley called Stocker’s Bottom. With permanent water and ample grass for herbivores, it’s one of our most active areas for kangaroos, wallabies and introduced deer, as well as smaller animals like wombats, bandicoots and quolls. Birds of all kinds frequent the area too, and we usually have swans nesting in the dam in spring. It’s also the most heavily modified part of The Quoin, and a site for future regeneration efforts. It’s the green valley at the top of this map:
The name long pre-dates our tenure, going back to the early days of the colony. “Stockers Bottom” is in the centre-left in this detail of an 1854 map of “Tasmania or Van Diemen’s Land” (click through to see the whole map), showing our closest town Ross at far left and the Freycinet Peninsula on the right.
The early European explorations of Lutruwita/Tasmania were conducted by sea, so maps from that period show coastal features in detail while leaving much of the island’s interior blank. As the colony grew in the early-1800s, extending northwards from Hobart and south from Launceston, surveyors partitioned the land into geometric lots, assigning private ownership to colonists and their convict workforce. The colonial process pushed out the Palawa and Pakana, whose custodianship had shaped the island’s ecosystems for tens of thousands of years.
The early maps of the island reflect their origin as tools of settlement and control. This 1845 map shows the Stocker’s Bottom area with “Quoin Mountain” to the south-east and the apportionment of lands to different owners. Many of these boundaries remain in place today.
We use the technology available to us to understand our world. Aerial photography, spurred by technical advancements in World War II, started to become broadly available in the second half of the 20th century. The Tasmanian government began a program of photographing the state from the air in 1945, providing essential information infrastructure for mapping and planning.
We’re lucky to have aerial photographs of Stocker’s Bottom dating back over 75 years, available via the excellent Land Tasmania Aerial Photo Viewer, as well as ListMAP. If you’re interested in how your favourite part of the island has changed, they’re well worth exploring.
In the Aerial Photo Viewer, each blue rectangle represents an available aerial photograph from a specific flight path — here, we can see several covering Stocker’s Bottom between 1940 and 1950.
The full-frame photographs are fascinating in their own right. The first row shows 1949, 1968 and 1980, followed by images from 1987, 1997 and 2002.
In this article, we’ll be focusing on the western section of Stocker’s Bottom, seeing what we can learn from these aerial images.
To first help situate you: Dismal Creek rises in the nearby hills and enters from the north and east of our focus area, where it’s collected in a small dam. From there, water flows south-west towards the main dam, which also receives water from the Quoin plateau and the hills to the south.
The main dam has straight walls built of local stone. It’s quite shallow, and its water level rises and falls throughout the year. Water flows over the spillway westwards through a narrow winding valley towards Tinamirakuna/the Macquarie River.
This drone view looks north at Stocker’s Bottom in the late afternoon light in September 2022. The main dam sits full on the left, while the smaller upstream dam is just visible in the top right. The two dams are a little over a kilometre apart, but there is only about a five-metre drop between them.
1949
This is the first aerial image we have of the area. A century after colonisation and notwithstanding the construction of the dams, much of Stocker’s Bottom still appears to be largely as it was maintained by the Tyerrernotepanner (Stony Creek) people of the North Midlands Nation: “The country they occupied abounded in game, being lightly timbered and well grassed.” Aboriginal Tasmanians used cool fire for land management, encouraging open grassy woodland ideal for attracting and hunting herbivores such as kangaroos, wallabies and wombats.
Hundreds of mature eucalypts are visible in the hundred-hectare central section of this image.
1968
The 1968 image is of exceptional quality (as are other images from the same series across the state); it’s sharp, highly detailed, and it was taken with the sun high in the sky so the shadows are reduced. Compared to 1949, there are fewer trees, especially in the lower section. A new circular dam can be seen on the right-hand edge, relatively full compared to later images.
1980
This 1980 image was taken on 12 April, when the sun was relatively low in the sky, so the shadows are elongated. There are even fewer trees left in the landscape. Some are still standing, but have no leaves; they’re not healthy trees being cut down for timber, but trees dying in place.
A closer look at a stand of trees north-east of the dam shows almost all of them dying over a thirty-year period. One exception is a dense, round tree north of the dam, about half-way up the detail view, which is probably a blackwood (Acacia melanoxylon). It’s a small tree in 1968, but has grown to dominate the area in 1980 — and will continue to do so for another twenty years.
1987
For December 1987 we have a colour image! This gives us more information: low-lying parts of Dismal Creek show as darker green, and there is perhaps evidence, in the bright green of the less-treed areas, that exotic grasses are being cultivated. The white skeletons of dead trees litter the landscape.
However, the image is not as crisp as other black-and-white photographs, and it also brings interpretive challenges: different surveys use different cameras and film stocks, which in turn can change colour differently as they age. Is this image representative of what the land really looked like that day?
1993
In February 1993, the imagery returns to black and white. This far into summer, there’s little water in any of the dams, though the sun still reflects off the water in the main dam and the creek below. It’s hard to tell in the monochrome image, but it looks like some dead trees have been removed. The central area is becoming less textured compared to earlier images, but the north-eastern corner still has many large trees.
1997
Between 1993 and 1997, profound changes were made: channels have been dug to contain and constrain water flow, almost all the trees have been cleared, and a formed road enters from the south and heads out to the east. Patterns in the cultivated areas show that the landscape has been comprehensively modified, representing a final step in the conversion of land for industrial agriculture. The circular features in the north-east of the images are piles of dead wood, indicating trees have been chopped down to clear the landscape for grass. Additionally, a new small dam has been constructed just east of the main dam.
2002
At the end of summer in 2002, the grass seems thin, with higher areas looking dry and worn. The dead wood piles in the north-east are bleaching to white. The blackwood just north of the main dam seems to be faltering.
2006
In March 2006, the whole area is dry, the blackwood is gone, and patterns indicate the area has recently been harvested for hay.
2010
In April 2010 we have the good fortune to see the haymaking process in action! The detail view below clearly shows baled hay ready for collection.
2021
We became The Quoin’s custodians in June 2021. Alongside satellite maps, we also have RGB and lidar imagery from 2021 via our AgTwin digital twin. Not much has changed since 2010. A stand of wattles just north of the dam wall continues to grow: on the ground, we’re not seeing tree recruitment in the open areas, though we do get Eucalyptus pauciflora growing inside gorse patches south of the dam, where they’re protected from browsing.
The lidar ‘aspect’ analysis generates a view of the landscape that sees through vegetation and shows which way the ground is sloping — imagine different coloured lights illuminating the landscape from compass points. It clearly shows the channels and even the concentric cultivation furrows.
The ‘aspect/slope’ analysis uses the same aspect data, but modulates saturation to indicate the slope angle (more saturated = steeper; grey = flat). This subtler view reveals the shape of the landscape, clearly showing the texture of the trees and hills, contrasted with dam walls, channels and roads, as well as the deeply incised creek upstream of the main dam.
From recognition to regeneration
Looking back through these aerial photographs gives us more than a record of change — it gives us clues for how to manage the landscape in the years ahead.
We know, for example, that large gum trees were present across the plain, often at higher points; we also know that many died in situ. In response, we’re now creating ash beds where trees once stood, adding nutrients to the soil and providing opportunities for recruitment, and we’re using ecological burns to stimulate new growth.
Leaky weirs are helping to slow down the water flowing in the channels and rehydrate the soil. We’re using our understanding of the shape of the land to predict what will happen to the main dam’s water level if we rebuild the spillway to its original height — and that, in turn, can tell us where the water edges will be, and where we can plant wooly tea-tree and other species around the water to create a more diverse ecosystem, bringing in more birds and providing shelter for amphibians and small animals.
These are just a few examples. With improved satellite imagery, statewide aerial surveys and now drones allowing us to map the landscape at centimetre resolution, we’ll continue to use aerial imagery to guide our work.
We’ll keep embracing technology more broadly too. These photographs remind us how far our tools have come: as they continue to evolve, they offer us new ways to understand the land, to think about it over longer timescales, to be better stewards for the future.
This article was written by: Michael Honey
And edited by: Bronte McHenry, Karina West and Lisa Miller
The Quoin is a living laboratory, where we develop and deploy technologies, products and practices to accelerate regeneration at scale.
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